This invention lies in the field of medical electronic apparatus and is directed to such apparatus which is used for electrosurgical operations. It is more particularly directed to improvements in the conductor cables and switching means which are used in such appliances.
Medical electronic apparatus has been employed for many years for many types of diagnosis and treatment. One field in which there has been considerable growth recently is electrosurgery, in which a suitable generator provides a high frequency, high voltage current which is transmitted to a small surgical electrode having a thin knife-like type to be applied to a patient. The patient sits or lies on a patient plate and is grounded thereto, with the plate being connected by a further conductor back to the generator. The relatively extremely small area of contact by the electrode with the patient provides an intense current in a highly localized area, producing a cutting action. The current passes through the patient's body to the patient plate where the area of contact is so great that no burning effect occurs.
For cutting purposes, the generator is activated to produce a continuous sine wave signal. However, the same instrument may be used to apply to the wound after cutting in order to produce coagulation. For this purpose the generator may be selectively activated to produce a pulsing signal which produces the desired results. Switching means are available for the operator to selectively control an activating means for causing the generator to produce the desired type of current.
Suitable control switches may be mounted on the instrument panel of the generator to be operated by an assistant. The is generally considered to be unsatisfactory because of the delay involved in transmitting instructions. In other designs, foot operated switches are provided which may be controlled by the surgeon. However, this interferes with his mobility because he must stand in one place or move the foot switches about on the floor. Another system which is more desirable consists of a multiple cable conductor extending from the generator to the electrode holder. One conductor is connected to the electrode to carry the therapeutic current and two other conductors are selectively connectable to the therapeutic current conductor through switches to complete circuits back to the activating means for causing the generator to produce the desired mode of current.
While this is the most satisfactory of the three arrangements because the surgeon is free to move about and has instant control of the current modes, there are still various disadvantages in the devices previously available. The electrode holders and switches are larger and heavier than need be, and the compound cables are heavier and stiffer than necessary so that the use of these devices is annoying and tiring to the surgeon. The usual compound cable makes use of three multiple strand conductors, each encased in high voltage insulation, with the three conductors further encased in a sheath of high voltage insulation. Such cable is relatively stiff and heavy and also expensive. Since all of the components are rather expensive it is necessary to use them repeatedly and this adds the further difficulty and expense of sterilization before each use.